Leakage and coupling of square and double D magnetic couplers

Commercial high power Electric Vehicle (EV) Inductive Power Transfer (IPT) systems need to comply with leakage regulations while transferring the required power. The choice and design of the magnetic coupler (pad) topology heavily influences the power, efficiency and leakage of these systems. This paper seeks to highlight the advantages and disadvantages of two pad topologies, the Square Pad and the Double D Pad (DDP). A metric that combines coupling and leakage to provide a fair comparison between pads is introduced. Variations on the pads are investigated, including adding a ferrite core, changing the aspect ratio and reducing the coil dimensions while keeping the ferrite dimensions constant. Simulation results show that, in general, the DDP has advantages when misaligned in one direction, whereas the Square Pad's advantages arise when misaligned in the other direction.